Which macronutrient is essential for growth, tissue repair, and immune function, with a recommended daily intake expressed in grams?

• A. Carbohydrates
• B. Fats
• C. Protein
• D. Fiber

Answer: (C)

Protein provides the amino acids that are used to build and repair body tissues, and to form immune molecules such as antibodies and enzymes. Because of this, protein is the nutrient most directly linked to growth, tissue repair, and maintaining a robust immune response. Daily intake is measured in grams, often expressed per kilogram of body weight (roughly 0.8 g/kg/day for many adults; higher amounts may be advised for athletes or during pregnancy). In contrast, carbohydrates and fats mainly supply energy, while fiber, though important for digestion, is not a direct building block for tissues or immune components. So the nutrient that best fits the description is protein.